Vehicle suspension systems provide isolation from rough or uneven terrain and resistance to lateral roll of the vehicle's body during a turn. In a typical vehicle suspension system a combination of a coil spring and a damper provide reciprocating compressive movement of a wheel toward the vehicle and rebounding movement of the wheel toward the ground. The coil spring provides a suspending spring force that biases the wheel toward the ground and the damper provides a damping force that dampens both the suspending spring force and any impact force imparted by the road surface or hazards. The damper is typically a pressure type gas strut having a damper tube and a reciprocable piston rod. A lower spring seat is mounted to the damper tube and an upper spring seat is mounted to the piston rod. The coil spring extends between the lower spring seat and the upper spring seat.
In many suspension systems the damper tube is attached to a lower arm of the suspension and is pivotable relative to the lower arm. As a result, a pinch point may be formed between the lower spring seat and the lower arm. If material such as debris, rocks, ice, mud, snow, sludge and fluids (generally termed “foreign objects” herein) are trapped in this pinch point, the performance of the suspension system may be degraded. If the trapped materials are incompressible solids the damper tube and/or lower spring seat may be damaged when the damper tube pivots during operation of the suspension system.
Some current dampers include a single shield to guard against foreign objects, but such shields are effective only for deflecting large debris. Other dampers may include an elastomeric material proximate the spring seat, as indicated by U.S. Pat. No. 2,927,786, issued to Templeton, and U.S. Pat. No. 3,195,918, issued to Poole. Although the problem of foreign object incursion is not addressed in these patents, such a resilient material could be used to alter or reduce the area of the damper-mount pinch point to some degree. However, this is not an entirely satisfactory solution, since at least some portion of the pinch point would necessarily remain exposed in order for the damper tube to pivot properly. Some suspension systems include a spring guard to shield an automobile wheel from contact with a fractured portion of a strut spring, as in U.S. Pat. No. 4,822,072, issued to Preslicka, et al. A coil spring embedded in a protective material may also be utilized, as in U.S. Pat. No. 4,886,256, issued to Nishiyama, et al. Scrapers to remove ice from the piston rod of a shock absorber are also available, as exemplified by U.S. Pat. No. 5,584,368, issued to Larsson. A number of other shock absorbers include a dust cover or shield, such as U.S. Pat. App. Pub. No. 2003/0218286, filed by Miyazaki, et al. However, none of the available suspension systems and suspension components provide a satisfactory way to close off the aforementioned damper-mount pinch point and prevent ingress of foreign objects. The current art also fails to teach a way to close off the damper-mount pinch point that takes into account the constantly varying shape of the pinch point as the damper pivots during normal suspension operation, so as to keep foreign objects out of the pinch point. Thus, there is a need for a better way to resist entrapment of foreign objects within components of the suspension.